Originally Posted by farmpony84
I think the breed has something to do with it because it seems like warmbloods and TBs (in this area) are jumped higher at younger ages so my assumption would be that there is a different rate at which their little knees fuse... but I'm not jumping expert.
I was always under the notion that you don't jump a horse until it's five.....
I think it is more due to the fact that the Warmbloods and TB's are considered the Sport horses that these classes are planned to attract.
All horses regardless of breed follow a very similar maturity in bone development - ie the hocks and spine don not finish developing until the late 5yrs.
Mental maturity may be earlier or later with various breeds and like some people somer horses never 'Growq Up' muscle development through correct work may give the impression of maturity but this doesn't mean that bone development is also mature.